Is edible oil good for your health?

medicine : Cooking oil under suspicion

It shimmers golden yellow, smells aromatic and flatters the palate - cooking oil is not only welcome in the kitchen, but is also a healthy alternative to butter or lard. However, when it comes to a healthy heart, not all oils are the same. Researchers are particularly concerned about how healthy the ubiquitous omega-6 fats are. For some it may not be enough omega-6, for others recommend limiting consumption. A new study has now fueled the dispute.

Omega fatty acids, chemically bound as fats in plants, are essential for humans. He needs them in his metabolism and cannot produce them himself, so he has to take them in with the (mostly vegetable) food. They are unsaturated fatty acids, hydrocarbon chains with predominantly 18 carbon atoms.

The most important are three omega fatty acids: the monounsaturated oleic acid (omega-9, especially in olive oil), which has an "unsaturated" double bond on the ninth carbon atom; the diunsaturated (on the sixth and ninth carbon atom) linoleic acid (omega-6, in sunflower, corn and soybean oil and corresponding margarines) and the polyunsaturated (on the third, sixth, ninth carbon atom) linolenic acid (omega-3, linseed oil, rapeseed oil ). In addition, the omega-3 fatty acids eicosapentaenoic acid and docosahexaenoic acid occur in oily fish.

Since saturated fats of animal origin fell into disrepute in the western industrial nations and increasingly gave way to vegetable fats, the supply of omega fats has improved significantly. Omega-6s, especially linoleic acid, clearly dominate. Some researchers see this with mixed feelings. They fear that too much omega-6 can do more harm than good. It confirms a study that was recently published online in the British Medical Journal.

458 Australian men with heart disease between the ages of 30 and 59 took part in the study. Half were asked to avoid saturated fats and instead obtain up to 15 percent of their caloric needs with linoleic acid from safflower oil. Safflower oil contains extremely high levels of omega-6 and no omega-3. The other half of the participants received no advice on healthy eating.

When the scientists took stock after a good three years, they found that the group of omega-6 consumers had more deaths, including more fatal events from cardiovascular diseases. Does that mean that margarine is more harmful than butter and lard, as the British newspaper "Independent" commented? Even omega-6 skeptics among nutritionists and medical professionals would not go that far, especially since the study in the British Medical Journal has a flaw. It is the analysis of 40-year-old data believed to be lost. Much has changed in our lifestyle since then, which is why the study has "little relevance for today's diet", as Tom Sanders of London's Kings College told the Independent.

"The situation is confusing," admits Matthias Schulze. The scientist at the German Institute for Nutritional Research in Potsdam-Rehbrücke considers it difficult to recommend a single oil, but also points out that vegetable fats are generally healthier for the heart than animal fats. This is also the result of an analysis by Dariush Mazaffarian. The scientist from Harvard Medical School in Boston scoured the scientific literature for research that examined the influence of fat consumption on heart disease.

Mazaffarian found out, as he reported in the journal "Plos Medicine", that a higher proportion of unsaturated fats in the calorie intake, for example from vegetable oil or fatty fish, lowers the risk of heart attack or cardiac death. However, the researcher could not break down what proportion of the earnings went to the controversial omega-6.

Unlike Christopher Ramsden, a nutrition researcher at the US National Institutes of Health. In 2010 he presented an analysis in the British Journal of Nutrition in which he separately itemized the influence of omega-3 and omega-6 on the risk of heart disease. Ramsden's analysis of important studies showed that replacing saturated fats and the particularly risky trans fats with a mixture of omega-3 and omega-6 reduced the risk of heart attack and cardiac death by 22 percent. If only omega-6 was specifically increased, the risk to the heart rose by 13 percent.

"Our data do not justify calling on the population to consume more omega-6 fats," is Ramsden's conclusion. In doing so, he contradicts the American Heart Society, which continues to emphasize the benefits of omega-6 and so far recommends that at least five to ten percent of calories be absorbed through these fats. However, the company wants to revise its recommendations.

One cause of the potentially adverse effects of omega-6s could be that they promote inflammation, which in turn can damage the heart. Omega-3 fats from fish have the opposite effect.

Helmut Gohlke from the board of directors of the German Heart Foundation points out that when it comes to nutrition, it is the “total package” that counts. "The Mediterranean diet is best examined for its health benefits," says the heart specialist. So lots of fresh fruit and vegetables, plus fish or alternatively nuts and little animal fats and meat. On the other hand, omega-3 capsules with fish oil have not proven to be useful, as Gohlke's colleague Oliver Weingärtner from the Saarland University Hospital emphasizes. And on this occasion reveals that he uses butter for frying. In moderation, of course.

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